Users can find GSM network providers by looking up regional and national carriers and either checking their websites or contacting them to find out which network technology they use. The major national GSM carriers are T-Mobile and AT&T, notes CNET.com. Some examples of regional GSM carriers include Blue Sky Mobile, Cellular One and Cordova Wireless.
Users can sometimes tell if a network provider is GSM by looking at the network specifications of the types it offers or an information page for those who wish to transfer service. For example, T-Mobile states that it is a GSM provider on its information page for bringing one's own phone to the service, and users can also use a search tool to find out if a device from a previous carrier is an unlocked GSM phone.
Cellular providers usually also have either online chat or phone options where interested customers can ask questions about the network, including whether it is GSM and whether an existing phone is compatible.
Those interested in the national GSM carriers T-Mobile and AT&T can visit the carriers' websites to get information on coverage where they live. T-Mobile is known for having less service in rural places than does AT&T, a much larger carrier, mentions CNET.com.
Some more regional GSM carriers to consider include KTC PACE in Louisiana; iWireless in Iowa, Wisconsin and Illinois; GCI Wireless in Alaska and OTZ Cellular in Alaska.